Scientists create wireless, resorbable sensor to monitor brain and other organs

By John Murphy, MDLinx
Published January 18, 2016

Key Takeaways

A new wireless sensor can monitor intracranial pressure and temperature in the brain and then be resorbed by the body, which minimizes infection and skips the need for surgical removal, according to an article published online January 18, 2016 in the journal Nature. The device could be formatted for other organs as well, researchers noted.

“A major hurdle has been that implants placed in the body often trigger an immune response, which can be problematic for patients. The benefit of these new devices is that they dissolve over time, so you don’t have something in the body for a long time period, increasing the risk of infection, chronic inflammation, and even erosion through the skin or the organ in which it’s placed,” said co-first author Rory KJ Murphy, MD, a neurosurgery resident at Washington University School of Medicine and Barnes-Jewish Hospital in St. Louis, MO.

“Plus, using resorbable devices negates the need for surgery to retrieve them, which further lessens the risk of infection and further complications,” Dr. Murphy added.

The wireless implant could be used for a variety of applications, Dr. Murphy said, although he is primarily focused on traumatic brain injury. “The devices commonly used today are based on technology from the 1980s. They’re large, they’re unwieldy, and they have wires that connect to monitors in the intensive care unit. They give accurate readings, and they help, but there are ways to make them better,” he said.

To that end, Dr. Murphy and other researchers developed their wireless implant, the smallest version of which is no bigger than a pencil tip—1 mm x 2 mm x 0.08 mm. It’s constructed mainly of polylactic-co-glycolic acid (PLGA) and silicon, and encapsulated with a polyanhydride film.

In in vivo experiments in rats, the device operated continuously for up to 3 days and remained “relatively constant” for 7 days, the researchers noted. After that, it degraded markedly. The experiments also showed that the wireless implants were just as accurate as commercial, wired sensors for monitoring intracranial pressures and temperature values.

“With advanced materials and device designs, we demonstrated that it is possible to create electronic implants that offer high performance and clinically relevant operation in hardware that completely resorbs into the body after the relevant functions are no longer needed,” said John A. Rogers, PhD, Professor of Materials Science and Engineering and Director of the Frederick Seitz Materials Research Laboratory at the University of Illinois at Urbana-Champaign, in Urbana, IL. “This type of bio-electric medicine has great potential in many areas of clinical care.”

The sensor can be used to monitor fluid flow, motion, pH, or thermal characteristics, and made compatible for use in the deep brain as well as in the heart, intra-abdominal organs, and limbs, the authors wrote.

Now that the researchers have shown that the device is accurate and can be resorbed in the brains of rats, they plan to test the implant in humans.

“The ultimate strategy is to have a device that you can place in the brain—or in other organs in the body—that is entirely implanted, intimately connected with the organ you want to monitor, and can transmit signals wirelessly to provide information on the health of that organ, allowing doctors to intervene if necessary to prevent bigger problems,” Dr. Murphy said. “And then after the critical period that you actually want to monitor, it will dissolve away and disappear.”

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